This invention relates to apparatus and methods for determining the position and quality of a component held on a component holding means. More particularly, this invention relates to apparatus and methods for location of an integrated circuit chip, also known as a die, precisely with respect to the transfer means of a die bonding apparatus. The quality of a chip to be transferred by the die bonding apparatus is also determined.
In the production of electronic circuitry using computer assisted systems there is a need for extremely rapid and accurate placement of the chip or die on a substrate. In many applications a plurality of chips to be placed on the substrate are removably held upon an adhesive film prior to being placed on the substrate. Each chip must be removed or extracted from the film by the system and rapidly transferred to the substrate. In order to effect a proper transfer of the chip, it is necessary to precisely locate the chip relative to the tool or tools used to transfer the chip from the film to the substrate.
Rapid production of high quality chip/substrate assemblies using computer assisted systems also requires a precision apparatus which incorporates effective quality control features. For example, it is common that a certain percentage of the chips held upon the adhesive film are defective or of substandard quality. In many applications, the chips held on the adhesive film are inspected for defects prior to being placed upon the chip transfer apparatus. It is common in these situations to place a relatively dark dot on a chip which is identified by the computer assisted assembly system as being defective or of substandard quality. In order to maximize the overall efficiency of the bonding apparatus, it is desirable to bypass the chips which have been so marked, leaving them on the adhesive film and thereby minimizing the time spent producing defective chip/substrate assemblies. It is thus desirable to have a method and apparatus by which not only the location of the chip contained on an adhesive film is precisely determined but also the quality of that chip as well.
Due to the small size of modern electrical components, particularly semiconductor chips or dice, assembly of these components requires extreme precision and care. If an assembly process requiring this precision and care was carried out manually, i.e., by a human operator, the cost of production would be relatively expensive. In addition, the work would be so tedious so as to increase the likelihood of poor quality control. Accordingly, previous work in the field of the present invention has utilized computer assisted systems for locating and manipulating the tiny components. For example, see U.S. Pat. No. 4,441,205 - Berkin and U.S. application Ser. No. 735,839, filed May 20, 1985, now abandoned, both assigned to the assignee of this invention.
Accordingly, it is an object of the present invention to provide a pattern recognition system in which the location of the chip held on an adhesive film is precisely determined.
It is another object of this invention to provide a pattern recognition system by which a defective chip or die is rapidly identified.
It is a still further object of this invention to provide a pattern recognition system which operates automatically and without significant help from a human operator.
It is yet another object of this invention to provide an image processing system and method for a die bonding apparatus having an improved capacity over manual techniques.
It is another object of this invention to provide an image processing system and method which, by employing reflected light, is capable of distinguishing between a defect indicating dot and the dark areas of the die.
It is another object of this invention to provide an image processing system and method which accurately determines the edges of a die on a sawn wafer.
It is a still further object of this invention to provide an image processing system and method for a die bonding apparatus which is capable of accurately positioning a die with respect to the transfer tool of the die bonding apparatus.